In contemporary telecommunications systems including mobile stations and cellular Base Stations (BS), calls to a mobile user are typically initiated by paging the mobile station. The mobile station (MS) is then enabled from a dormant state to an active state and a traffic channel is set up. Note that in this specification the term mobile station (MS) refers to a wireless communication device, which will typically be a mobile device (e.g., cellular telephone), but also includes fixed wireless devices which are not mobile.
A number of methods and devices exist in the prior art that attempt to reduce latency in waking up dormant communication devices and setting up a call. One such prior art reference is U.S. Pat. No. 6,725,053 issued to Rosen et al. on Apr. 20, 2004 and herein incorporated by reference. The Rosen et al. patent discloses a method and apparatus for reducing dormant-wakeup latency in a group communication network and seeks to reduce the actual total dormant-wakeup time and the Push-to-Talk (PTT or P2T) latency perceived by a talker through caching the network-initiated wakeup triggers destined for target listeners, and delivering a wakeup trigger to a target mobile station as soon as the target mobile station has re-established its traffic channel.
PTT is an emerging voice-based value added service application for many leading mobile communications service providers including CDMA2000 networks. A PTT call or session involves two or multiple parties and combines aspects of cellular mobile communications, presence detection, and walkie-talkie style communications. PTT provides end-users with the ability to quickly find one another and engage in brief, burst-oriented style communication. Advances in market adoption and technology evolution of voice over wireless Internet Protocol (IP) will enable improvements in PTT. Rather then being a replacement of long, interactive communication, PTT is best suited for demands for quick communication among end-users. Due to the fact that PTT is provided in half-duplex mode (i.e., transmission occurs in both directions, but not at the same time such that each party must wait to speak), the inability to interrupt lends itself to quick exchanges of Information. A PTT system in CDMA2000 typically involves PTT mobiles, the CDMA2000 access network, and the PTT server.
During a PTT session, before a party can speak that party needs to push the PTT button on the handset to request the floor. The PTT server will arbitrate call requests among the group members and grant the floor on a first come, first serve basis or user priority. Upon receiving the floor grant (which is indicated as a beep on the handset), the PTT member can start talking while holding down the PTT button. The remaining group members will be in the listening mode as only one member can speak at any given time. Once the talker finishes their speech, they will release the floor by letting go the PTT button. Others may then push the PTT button on their handsets to request for the floor and start talking.
A PTT session or call has to be set up before the group members can engage in conversation. Within a CDMA2000 network, PTT call setup includes call origination and call termination. PTT call origination typically involves the following steps: (1) a PTT mobile signals (using IS2000 signaling messages) to the CDMA2000 access network to setup traffic channels and network connections so that PTT application traffic (signaling and voice) can be carried between the mobiles and the PTT server; (2) PTT mobiles signal (typically using Session Initiation Protocol (SIP) or some proprietary application level signaling protocol) to the PTT server to invite others to join the PTT call; and (3) upon receiving confirmation from the terminating mobiles (called parties), the PTT server will issue a floor grant to the originating mobile (the calling party). The calling party can then start talking.
A PTT call termination involves the following steps: (1) the PTT server sends invite messages to the access network for delivery to the called parties; (2) the access network locates the called PTT mobiles and exchange IS2000 signaling to setup traffic channels and then deliver the invite messages to the called PTT mobiles; and (3) the PTT mobiles respond to the PTT server to either accept or reject the invite.
There are two major performance metrics to PTT call setup: (1) “Push-to-Beep” which is the time from when the caller pushes the PTT button to when the Caller is granted the floor; and (2) Push-to-Receive which is the time from when the caller pushes the PTT button to when the voice packets arrive at the called party's mobile terminal. The above call setup process is not optimal and the push-to-beep time usually takes 4-7 seconds. The main problem is that it is strictly a sequential process where a traffic channel has to be setup to send PTT application signaling (i.e., SIP messages). Ideally, enabling some degree of parallelism by allowing transmission of PTT application signaling (i.e., SIP) while setting up the traffic channel between the mobile and the access network would be advantageous.
Using the short data burst (SDB) feature of CDMA2000 can offer some degree of parallelism. The SDB feature allows transmission of small amounts of data between the mobile and network using CDMA common channels (e.g., access channel and paging channel), without having to setup a traffic channel. For PTT call setup, the originating mobile can first send a SIP invite message to the PTT server using a SDB, then start traffic channel setup. This allows the PTT server to initiate call setup with the called parties (terminating mobiles) while the originating mobile is going through the traffic channel setup process. This helps reduce the end-to-end PTT call setup time.
In addition to PTT applications, other SIP-based applications including, but not limited to voice over Internet protocol (VOIP) applications also suffer from delays in call setup within the wireless realm.
A solution for reducing these delays is taught in Commonly assigned co-pending application Ser. No. 10/879,007, which is hereby incorporated by reference.
Another difficulty to overcome resides in the fact that existing systems do not provide indications about the nature of packet data to the wireless access network. Accordingly, it is difficult to use SDB to a terminating mobile station, when the Wireless Access network receives packet data without an indication that the data is suitable for a SDB transmission.
For example, one problem that exists today is that the Packet Control Function (PCF), which typically is associated with the Base Station Controller (BSC), has limited knowledge about the nature of the packet data arriving from the Internet, on a bearer path connected via the Packet Data Serving Node (PDSN), and cannot make an intelligent decision on its own as to how best to handle the packet data. As far as the PCF is concerned, received packets simply appear as byte streams on the bearer path to be forwarded via the BSC to the Mobile Station (MS). Thus, the system can not easily determine that SDBs can be used beneficially for the underlying applications.
This problem is not limited to decisions regarding when SDBs can be best utilized, but generally limits the wireless access network from making the best use of all resources available to it.
It is, therefore, desirable to provide a solution that allows the Wireless Access Network and the PDSN to better utilize the resources available to it, including making intelligent decisions as how to best handle packet data received from a packet data network (for example, the Internet).